Gender bias in family formation in China is well documented. Much less is known abouthowchildren fare once theybecome part of afamily. Drawing onfieldwork and survey data, we describe the care ofyoung children, and investigate the relationship between the one-child policy and parental involvement in care. Results indicate that theone-child policy, insofar asit limitscouples to oneor twochildren, leads togreater involvement byparents in child care. Additional effects ofpolicy vary bychildren's gender. Boys receive similar care regardless of theone-child policy in their communities. Girls, living in communities where couples are permitted another child if theirfirst isa girl, are more likely to receive parental care thangirls in other communities. These results suggest thatgender bias in China isnot solely due to outdated "feudal" ideas resulting in son preference.China, through the one-child policy, has instituted the most aggressive, comprehensive population policy in the world. This policy, first instituted in late 1979, followed on the heels of China's dramatic fertility decline. The total fertility >I-This research was supported by a fellowship from the Population Council and a grant from NICHD (ROI-HD37877). We are also grateful for the support provided by the Carolina Population Center and the Brown Population Studies and Training Center. Funds for parts of the project design,

Chalcogenide-based anodes are receiving increasing attention for rechargeable potassium-ion batteries (PIBs) due to their high theoretical capacities. However, they usually exhibit poor electrochemical performance due to poor structural stability, low conductivity and severe electrolyte decomposition on the reactive surface. Herein, a method analogue to "blowing bubbles with gum" is used to confine FeS2 and FeSe2 in N-doped carbon for PIBs anodes with ultrahigh cyclic stability and enhanced rate capability (over 5000 cycles at 2 A g −1 ). Several theoretical and experimental methods are employed to understand the electrodes' performance.The density functional theory (DFT) calculations showed high affinity for potassium adsorption on the FeS2 and FeSe2. The in-situ XRD and ex-situ TEM analysis confirmed the formation of several intermediate phases of the general formula KxFeS2. These phases have high conductivity and large interlayer distance, which promote reversible potassium insertion and facilitate the charge transfer. Also, the calculated potassium diffusion coefficient during charge/discharge further proves the enhanced kinetics. Furthermore, The FeS2@NC anode in a full cell also exhibits high cyclic stability (88 % capacity retention after 120 cycles with 99.9 % Coulumbic efficiency). Therefore, this work not only provides an approach to overcome several challenges in PIBs anode but also a comprehensive understanding of the mechanism and kinetics of the potassium interaction with chalcogenides.

Rechargeable alkali metal‐ion batteries (AMIBs) are receiving significant attention owing to their high energy density and low weight. The performance of AMIBs is highly dependent on the electrode materials. It is, therefore, quite crucial to explore suitable electrode materials that can fulfil the future requirements of AMIBs. Herein, a hierarchical hybrid yolk–shell structure of carbon‐coated iron selenide microcapsules (FeSe2@C‐3 MCs) is prepared via facile hydrothermal reaction, carbon‐coating, HCl solution etching, and then selenization treatment. When used as the conversion‐typed anode materials (CTAMs) for AMIBs, the yolk–shell FeSe2@C‐3 MCs show advantages. First, the interconnected external carbon shell improves the mechanical strength of electrodes and accelerates ionic migration and electron transmission. Second, the internal electroactive FeSe2 nanoparticles effectively decrease the extent of volume expansion and avoid pulverization when compared with micro‐sized solid FeSe2. Third, the yolk–shell structure provides sufficient inner void to ensure electrolyte infiltration and mobilize the surface and near‐surface reactions of electroactive FeSe2 with alkali metal ions. Consequently, the designed yolk–shell FeSe2@C‐3 MCs demonstrate enhanced electrochemical performance in lithium‐ion batteries, sodium‐ion batteries, and potassium‐ion batteries with high specific capacities, long cyclic stability, and outstanding rate capability, presenting potential application as universal anodes for AMIBs.

Ochratoxin A(OTA) is found to be one of the predominant contaminating mycotoxins in a wide variety of food commodities. To avoid the risk of OTA consumption, the detection and quantitation of OTA level are of great significance. Based on the fact that ssDNA aptamer has the ability to form a double-strand structure with its complementary sequence, a simple and rapid aptamer-based label-free approach for highly sensitive and selective fluorescence detection of OTA was developed by using ultra-sensitive double-strand DNA specific dyes PicoGreen. The results showed that as low as 1 ng/mL of OTA could be detected with a dynamic range of more than 5 orders of magnitude which satisfies the requirements for OTA maximum residue limit in various food regulated by European Commission. With the specificity of aptamer, the assay exhibited high selectivity for OTA against two other analogues (N-acetyl-l-phenylalanine and zearalenone). We also tested the aptasensor practicability using real sample of 1% beer spiked with a series of concentration of OTA and the results show good tolerance to matrix effect. All detections could be achieved in less than 30 min, which provides a simple, quick and sensitive detection method for OTA screening in food safety and could be easily extend to other small molecular chemical compounds detection which aptamer has been selected.

Droplet microfluidics has enabled the synthesis of polymeric particles with controlled sizes, shell thickness, and morphologies. Here, we report the Janus to core-shell structural evolution of biphasic droplets formed in a microfluidic flow-focusing device (MFFD) for the synthesis of polymer microcapsules with oil core/thickness-tunable shell via off-chip photo-and thermally induced polymerization. First, nanoliter-sized biphasic Janus droplets comprising an acrylate monomer and silicone oil were generated in a co-flowing aqueous polyvinyl alcohol (PVA) solution in an MFFD on a glass chip. Immediately following their break-off, the produced Janus droplets started to change their geometry from Janus to core-shell structure comprising a single silicone-oil core and an acrylatemonomer shell by the minimization of interfacial energy. Thus, we could produce monodisperse coreshell drops with average diameters of 105-325 μm, coefficient of variation (CV) values of 1.0-4.5%, and shell thickness of 1-67 μm. Subsequently, these drops were synthesized to fabricate polymeric microcapsules with tunable shell thickness via photo-and thermally induced polymerization. By increasing the concentration of the photo-and thermal initiator, we successfully produced thinner and ultra-thin shell (800 nm thickness) microcapsules. The surface structure of resulting particles was smooth in photopolymerization and porous in thermal polymerization. Microcapsules with core-shell structures, in which the active substances in cores are protected by the shells from the outer environment, have been applied in numerous fields such as foods 1,2 , cosmetics 3,4 , pharmaceutics 5 , printing 6,7 , and self-healing materials 8,9. Microcapsules can be synthesized via a variety of techniques including spray drying 10 , layer-by-layer deposition 11 , interfacial polymerization 12 , coacervation 13 , or membrane emulsification 14. Although these techniques can provide a high throughput, it remains difficult to fabricate uniform microcapsules with controlled size and high encapsulation efficiency. Recently, droplet microfluidics has been shown to provide a new and promising route to synthesize microcapsules. Using microfluidic technology, one can easily produce monodisperse core-shell droplets as ideal templates for fabricating microcapsules via subsequent various solidification methods; examples of the solidification methods include photo or thermally induced free-radical polymerization 15,16 , solvent evaporation 17 , freezing 18 , and ironic cross-linking 19. So far, the core-shell templates were prepared in two-step or one-step droplet formation. In the two-step method, using two T-junctions 20,21 , two flow-focusing junctions 22,23 , two co-flowing junctions 24 , or three-dimensional devices 25 , core drops are generated at first and then shell drops encapsulating these core drops are produced in a continuous phase as a separate step. Using this two-step approach, for example, acrylic capsules with aqueous cores with diameters of 10-340 µm and CVs ~5% ...

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The properties of polyelectrolyte brushes can be controlled by hydrogen bonding between the bound counterions and the grafted chains.

Electronic metal–support interactions (EMSI) describe the electron flow between metal sites and a metal oxide support. It is generally used to follow the mechanism of redox reactions. In this study of CuO‐CeO2 redox, an additional flow of electrons from metallic Cu to surface carbon species is observed via a combination of operando X‐ray absorption spectroscopy, synchrotron X‐ray powder diffraction, near ambient pressure near edge X‐ray absorption fine structure spectroscopy, and diffuse reflectance infrared Fourier transform spectroscopy. An electronic metal–support–carbon interaction (EMSCI) is proposed to explain the reaction pathway of CO oxidation. The EMSCI provides a complete picture of the mass and electron flow, which will help predict and improve the catalytic performance in the selective activation of CO2, carbonate, or carbonyl species in C1 chemistry.